Prediction Score for DAPT Beyond 1 Year After PCI
What are the predictors that identify patients expected to derive benefit versus harm from continuing thienopyridine beyond 1 year after percutaneous coronary intervention (PCI)?
Among 11,648 randomized DAPT (Dual Antiplatelet Therapy) study patients from 11 countries (August 2009-May 2014), a prediction rule was derived stratifying patients into groups to distinguish ischemic and bleeding risk 12-30 months after PCI. Validation was internal via bootstrap resampling and external among 8,136 patients from 36 countries randomized in the PROTECT (Patient-Related Outcomes With Endeavor vs Cypher Stenting) trial (June 2007-July 2014). Twelve months of open-label thienopyridine plus aspirin was administered, and then patients randomized to 18 months of continued thienopyridine plus aspirin versus placebo plus aspirin. The main outcomes measures were ischemia (myocardial infarction or stent thrombosis) and bleeding (moderate or severe) 12-30 months after PCI.
Among DAPT study patients (derivation cohort; mean age, 61.3 years; women, 25.1%), ischemia occurred in 348 patients (3.0%) and bleeding in 215 (1.8%). Derivation cohort models predicting ischemia and bleeding had c-statistics of 0.70 and 0.68, respectively. The prediction rule assigned 1 point each for myocardial infarction at presentation, prior myocardial infarction or PCI, diabetes, stent diameter <3 mm, smoking, and paclitaxel-eluting stent; 2 points each for history of congestive heart failure/low ejection fraction and vein graft intervention; −1 point for age 65 to younger than 75 years; and −2 points for age 75 years or older. Among the high score group (score ≥2, n = 5,917), continued thienopyridine versus placebo was associated with reduced ischemic events (2.7% vs. 5.7%; risk difference [RD], −3.0%; 95% confidence interval [CI], −4.1% to −2.0%; p < 0.001) compared with the low score group (score <2, n = 5,731; 1.7% vs. 2.3%; RD, −0.7%; 95% CI, −1.4% to 0.09%; p = 0.07; interaction p < 0.001). Conversely, continued thienopyridine was associated with smaller increases in bleeding among the high score group (1.8% vs. 1.4%; RD, 0.4%; 95% CI, −0.3% to 1.0%; p = 0.26) compared with the low score group (3.0% vs. 1.4%; RD, 1.5%; 95% CI, 0.8-2.3%; p < 0.001; interaction p = 0.02). Among PROTECT patients (validation cohort; mean age, 62 years; women, 23.7%), ischemia occurred in 79 patients (1.0%) and bleeding in 37 (0.5%), with a c-statistic of 0.64 for ischemia and 0.64 for bleeding. In this cohort, the high-score patients (n = 2,848) had increased ischemic events compared with the low-score patients, and no significant difference in bleeding.
The authors concluded that among patients without major bleeding or ischemic events 1 year after PCI, a prediction rule assessing late ischemic and bleeding risks to inform DAPT duration showed modest accuracy.
This study suggests that among patients not sustaining major bleeding or ischemic events 1 year after PCI, a prediction score assessing late ischemic and bleeding risks to inform DAPT duration showed modest accuracy in derivation and validation cohorts (c-statistic of 0.64). It should be noted that the score was designed for the ‘DAPT’ like population of patients who do not have events for the first 12 months, who do not have contraindications to DAPT, and who are tolerating dual therapy. Thus, caution is indicated for use of this prediction score until further validation in other cohorts is performed, and optimal clinical and procedural care to reduce overall bleeding and ischemic risks should be practiced independent of a patient’s score.
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